Limit switch actuator



Dec. 23, 1947 E. 6. WHITE LIMIT SWITCH ACTUATOR Filed June 14, 1943 .12f Ezrlu/bi INVENTOR. 14 '2 BY fiaawmy' 116 4 Mme Patented Dec. 23, 1947UNITED STATES PATENT O F FIC E SWITCH ACTUATOR Earl White, Hobart, Ind.

Application June 14., 1943.. Serial No. 490.727

3 Clai'ms; I

My invention relates to improvements in limit switch actuator and moreespecially includes the features pointed out in the annexed claims.

The purpose of my invention is to provide a safety feature to beattached to an overhead crane or on a locomotive crane to release analarm in the operators cabin whenever the crane reaches a predeterminedpoint of danger that the alarm is operated during the forward or rearmovement of the crane; that it is automatically inoperative when thecrane moves away from the danger zone. However, the alarm is eiiectivewithin short lengths of travel or longer distances determined by anydesired limit means placed in the path of travel. The device is simplein its construction and it is elfective under changing circumstances.

With these and other ends in View I illustrate on the accompanyingdrawing such instances of adaptation as will show the broad features ofthe invention without limiting myself to the specific details shownthereon and described herein.

Figure l is a top plan.

Figure 2 is a side elevation.

Figure 3 is a diagrammatic View of the restoring mechanism.

Figure 4 is a diagrammatic View of the circuit closing featuresassociated with a control switch.

Figure 5 is a detached diagram of a non-pivoted switch.

Figure 6 is a detached detail of an elastic connection between theswitch and the pilot limiting arm.

Figure 7 is an enlarged plan in section of a pair of interrolling guidewheels.

Figure 8 is an elevation of Fig. 7.

Figure 9 is an elevation in section of a pair of interacting groovedidling rollers.

Figure 10 is a diagram of a simple alarm circuit.

In practicing my invention I do not limit myself to the specific detailsof mechanism of construction and operation that the varying exigenciesof operation may demand without depart ing from the broad concept of theinvention,

My safety alarm is positioned in an attachable and detachable manner onan overhead traveling or a locomotive surface traveling crane, at one ormore positions on the crane, in such a relation that a pilot lever willoperate an alarm signal in the operators cabin. The pilot lever may bep0 sitioned at any desired place on the crane and the trip may beattached to the frame work of the overhead track for the crane, or itmay be placed alon side of the path of travel at any desired point.

The movement limiting feature may be a stake in the ground in the pathof travel of a surface locomotive crane. These limits are adjustable,that is they may be placed anywhere in advance of a danger zone and theyare so positioned that as the crane travels on its tracks the pilot armwill engage the stop before the danger zone is reached. The stop may beany desired stake or arm placed in changeable positions in the path ofthe moving crane.

In its simplest form my alarm is mounted on a base I that is permanentlyattached to or clamped to the frame of a crane in an desired manner. It.may be located at different points on the crane, in duplication orotherwise so that the safety factor of my device will come into play, ineither direction of the movement of the crane.

The base I is attached to any desired part of a crane so that its pilotarm or trip lever 2 will project forward of the base in any desireddirection so that the arm 2 will engage a trip 3 placed at any desiredpoint in the path of travel of the crane on the track frame or on theground.

The front end of the pilot or trip arm 2 is formed of two reverse curves4. This is so shaped that its range of action is increased over thatsecured by a simple straight sided trip arm. It is pivoted to the baseplate at 5. Its short end 6 is attached to a restoring cable I. Thiscable passes through between the adjacent grooves 8 of a pair of idlerpulleys 9. It then passes rearward and is attached to a restoring springIll. The pivot 5 is in line with the spring Ill and the grooved opening8 between the two idlers 9.

When the short end 6 of the arm 2 moves to either side of its center itis against the tension of the spring In which restores the pilot arm 2to its central position regardless of the direction that the arm ismoved around its pivot 5. This always returns the pilot arm to itsneutral position.

At the same time that the arm 2 moves around its pivot 5, in eitherdirection a plate ll attached to it above the pivot moves with it. Thisplate is connected to an ordinary switch 12 by means of a conventional"bead chain l3. This chain is attached to a spring M which in turn isconnected to two pins l 5 on the plate I l by means of a separate chainHi. When the arm 2 is in neutral position the chain l6 forms a trianglewhich includes the two interconnected pins IS. A link I! may be placed,above the chain it and on the pins I5. It prevents the chain l6 becomingtangled with one of the pins when the arm 2 is moved into an extremeposition.

The switch I2 is supported in a frame l8 that may be pivoted at l9 toconform to the move- 3 ment of the arm 2 as it is shifted to the rightor the left. A rod 20' attached to the frame l8 and the spring I 4serves to hold the bead chain l3 in alignment with the spring 14, chainl6 and one pin l5.

The rollers 9 are mounted on a base 2| and they turn on pivot pins 22.One of the rollers 9 has a larger diameter circumferential tongue 23 oneach side of the groove 8 and the companion roller has a groove 24 inwhich the tongue 23 freely enters. This construction serves to hold thecable 1 in the roller groove 8 against accidental displacement. A yoke25 may be placed above the rollers 9. It assists in holding the pins 22in spaced-apart relation.

I do not limit myself to the arrangement of parts shown on Fig. 4 as theswitch frame 26 may be secured to the base I in any desired manner asshown in Fig. 5. The bell end 21 is adapted to a free movement of thehead chain 13 as is usual in conventional practice.

What I claim is:

l. A pilot arm of a traversing circuit closer which comprises anattachable and detachable base, a pilot arm pivoted on the base formovement said arm extending from the pivot to engage a safety tripexternal of the base and in the path of said traverse, a short extensionfrom the arm on the opposite side of the pivot, a cable, a spring havingone end of it secured to the base and the other end attached to thecable and the cable in turn attached to the short end of the pilot arm,a pair of grooved rollers one on each side of the cable positioned sothat the cable passes freely between the adjacent grooves and serves tohold the pilot arm in a neutral position.

2. A relatively long pilot arm adapted to engage a safety stop whichcomprises opposite curved edges, a pivot for the arm, a short extensionto one side of the pivot, a cable attached thereto, a spring attached tothe cable, a base to which the spring is attached and on which the armis pivoted, and a pair of rollers having inter engaging grooves betweenwhich the cable passes, said adjacent grooves, the spring and the armpivot being on approximately the same vertical plane.

3. A traversing circuit closer comprising a relatively long arm, a pivottherefor, a short extension to one side of the pivot, a lateralextension above the short extension, an elastic connection from thelateral extension to a circuit closer, an elastic connection from theshort extension, a base for the parts, means for automatically holdingthe arm in a neutral position, and means for operating the circuitcloser when the arm is moved a predetermined distance to either side ofits neutral position by a trip in the path said arm traverses,

EARL G, WHITE.

REFERENCES CETED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,426,193 Holmgren Aug. 12, 19221,483,173 Gordon Feb. 12, 1924 1,671,615 Spahr May 29, 1928 1,902,700Hadano Mar. 21, 1933

